A top drive can be used in a drilling rig for handling a pipe string during drilling or lining a wellbore. In some well operations, an engaging apparatus, including an internal or external pipe gripping mechanism, can be connected below the top drive to grip a joint of pipe, such as casing, so that the engaging apparatus and the joint of pipe can be driven axially and/or rotationally by the top drive. Some engaging apparatus for casing pipe are described in U.S. Pat. No. 6,311,792, issued November 2001 and International application WO00/05483, published February 2000, both to TESCO Corporation.
In a drilling rig, the top drive can be hung in the mast with the engaging apparatus connected in drive communication and in substantial axial alignment therebelow. The top drive and engaging apparatus are hung in the mast above the well center, the top drive and engaging apparatus define a main axis of the drilling rig that is aligned with well center. Joints of pipe, for connection into the drill or liner string, can be supported, for example in a V-door, adjacent the main axis of the drilling rig. For connection into the drill or liner string, the pipe joints can be engaged by an elevator and brought under the drive system for engagement and handling. Generally, the elevator is supported on link arms suspended from the top drive or cables extending from the top drive link arms.
To pick up a pipe joint, the top drive is lowered to permit the elevator, either on conventional link arms or with the cables attached to the link arms, to be manually moved over and engaged about a pipe joint on the V-door. The top drive is then hoisted to pull the pipe joint off the V-door. Once free of the V-door, the pipe joint can be swung by gravity under the engaging apparatus so that the gripping mechanism can engage the pipe joint.